Chlorpyrifos exposure in farm families: Results from the farm family exposure study

Bruce H. Alexander, Carol J. Burns, Michael J. Bartels, John F. Acquavella, Jack S. Mandel, Christophe Gustin, Beth A. Baker

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38 Scopus citations


We used urinary biological monitoring to characterize chlorpyrifos (O,O-diethyl-O-(3,5,6-trichloro-2-pyridinyl) phosphororthioate) exposure to farm family members from Minnesota and South Carolina who participated in the Farm Family Exposure Study. Five consecutive 24-h urine samples were obtained from 34 families of licensed pesticide applicators 1 day before through 3 days after a chlorpyrifos application. Daily 3,5,6-trichloro-2-pyridinol (TCP) urinary concentrations characterized exposure profiles of the applicator, the spouse, and children aged 4-17 years. Self-reported and observed determinants of exposure were compared to the maximum postapplication TCP concentration. All participants had detectable (≥1 μg/l) urinary TCP concentrations at baseline. Applicators' peak TCP levels occurred the day after the application (geometric mean (GM)=19.0 μg/l). Postapplication TCP change from baseline in the spouses and children was negligible, and the only reliable predictor of exposure was assisting with the application for children aged 12 years and older. The applicators' exposure was primarily influenced by the chemical formulation (GM=11.3 μg/l for granular and 30.9 μg/l for liquid), and the number of loads applied. Repairing equipment, observed skin contact, and eating during the application were moderately associated TCP levels for those who applied liquid formulations. Estimated absorbed doses (μg chlorpyrifos/kg bodyweight) were calculated based on TCP excretion summed over the 4 postapplication days and corrected for pharmacokinetic recovery. The GM doses were 2.1, 0.7, and 1.0 μg/kg bodyweight for applicators, spouses, and children, respectively. Chlorpyrifos exposure to farm family members from the observed application was largely determined by the extent of contact with the mixing, loading, and application process.

Original languageEnglish (US)
Pages (from-to)447-456
Number of pages10
JournalJournal of Exposure Science and Environmental Epidemiology
Issue number5
StatePublished - Sep 26 2006

Bibliographical note

Funding Information:
The FFES was funded through a grant to the University of Minnesota by Bayer, Dow, DuPont, FMC, Monsanto, Syngenta, and the American Chemistry Council. We appreciate the cooperation of participating farm families and advice from sponsoring company scientists and the FFES Advisory Panel, chaired by Dr. Harris Pastides.


  • Biomonitoring
  • Chlorpyrifos
  • Epidemiologic studies
  • Pesticide exposure

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